a) Field of the invention
The present invention relates to a disc cartridge in which a shutter is arranged to open or close a record playback opening of a shell rotatably housing a disc-shaped recording medium and in which a spring force exerted by a shutter biasing spring biasing the shutter in a close direction can prevent the shutter from being projected from a front end surface of the shell.
b) Description of the related art
FIGS. 9 through 14 show a previously proposed disc cartridge, for example, a floppy disc cartridge.
The disc cartridge 101 includes: a disc-shaped recording medium 102; a shell 103 rotatably housing the disc-shaped recording medium; a shutter 105 opening and closing a record playback opening 104 installed on upper and lower surfaces 103a and 103b of the shell 103; and a spring 106 used for a biasing purpose of the shutter (a twisted coil spring) to bias the shutter 105 toward the opening 104 for the record playback purpose.
The shell 103 is provided with an upper surface 103a, a lower surface 103b, a front end surface 103c, and a recess 103d for attaching the shutter, the recess 103d constituting a shutter slide area. The above-described recess 103d is formed with the approximately same depth D as the thickness T of the shutter 105.
The shutter 105 includes: first and second shutter plate portions 105a and 105b overlapped on the shutter attaching recess 103d of the upper and lower surfaces of the shell 103; and a linkage plate portion 105c linked to each one end of the first and second shutter plate portions 105a and 105b and having an inner surface overlapped on the shutter attaching recess 103d of the front end surface 103c of the shell 103. In addition, the second shutter plate portion 105b is provided with front and second slide guide projections 107 and 108 disposed on one end and the other end of the plate portion 105b in its shutter slide direction.
The above-described shutter 105 is attached on the shell 103 so that the first and second slide guide projections 107 and 108 are inserted into first and second slide guide grooves 109 and 110 and are slid along these slide guide grooves 109 and 110.
The first and second slide guide grooves 109 and 110 are disposed on the upper surface 103b of the shell 103 in parallel to each other along the front end surface 103c of the shell 103.
The shutter biasing spring 106 has one end 106a engaged to a spring engagement portion 111 installed on a side portion of the shutter 105 on which the first slide guide projection 107 is attached and has the other end 106b engaged to an inner wall of the shell 103.
As typically shown in FIG. 11, a distance L11 from an inner surface (a surface opposed against a linkage plate portion 105c) of the first slide guide projection 107 to an outer surface of the linkage plate portion 105c of the shutter 105 and a distance L12 from an inner surface (the surface opposed against the linkage plate portion 105c) of the second slide guide projection 108 to the outer surface of the linkage plate portion 105c of the shutter 105 are formed to be equal to each other (L311=L12). In other words, both of the first slide guide projection 107 and the second slide guide projection 108 are arranged on the same straight line position in parallel to the linkage plate portion 105c of the shutter 105.
In addition, a distance L13 from the first slide guide groove 109 into which the first slide guide projection 107 is inserted to the front end surface 103c of the shell 103 and a distance L14 from the second slide guide groove 110 into which the second slide guide projection 108 is inserted to the front end surface 103c of the shell 103 are formed to be equal to each other (L13=L14).
In other words, the first slide guide groove 109 and the second slide guide groove 110 are arranged on the same straight line position in parallel to the front end surface 103c of the shell 103.
The shutter 105 is slidably attached on a shutter attaching recess 103d of the shutter 103 by inserting the shell 103 between the first and second shutter plate portions 105a and 105b from the front end surface 103c of the shell 103 and by inserting the first and second slide guide projections 107 and 108 into the first and second slide guide grooves 109 and 110, respectively.
However, in the disc cartridge 101 described in the BACKGROUND OF THE INVENTION, the spring force exerted by the shutter biasing spring 106 causes the one end of the shutter 105 to which the spring 106 is engaged to be projected from the front end surface 103c of the shell 103. Hence, the shell 103 becomes easy to be interfered against other parts. Dust becomes easy to be invaded into the shell 103. Or, a clearance xcex4 is developed between the side portion of the shutter plate portions 105a and 105b and the side portion 103e of the shutter attaching recess 103d of the shell 103. This clearance gives a user, to his eye, a kind of unstable sense of feeling and gives worse outer appearance.
Causes of the projection of the one end of the linkage plate portion 105c of the shutter 105 from the front end surface 103c of the shutter 103 was pursued.
As the result of this pursuit, one cause was determined.
That is to say, the cause was that the distance L11 from the first slide guide projection 107 to the outer surface of the linkage plate portion 105c of the shutter 105 and the distance L12 from the second slide guide projection 108 to the outer surface of the linkage plate portion 105c of the shutter 105 were formed to be mutually w the same value (L11=L12). In details, the cause was that the first slide guide projection 107 and the second slide guide projection 108 were arranged on the same straight line position in parallel to the linkage plate portion 105c of the shutter 105. In addition, the cause was that a distance L13 from the first slide guide groove 109 into which the first slide guide projection 107 was inserted to the front end surface 103c of the shell 103 and a distance L14 from the second slide guide groove 110 into which the second slide guide projection 108 was inserted to the front end surface 103c of the shell 103 were formed to be mutually the same value (L13=L14). In details, the first slide guide groove 109 and the second slide guide groove 110 were arranged on the same straight line position in parallel to the front end surface 103c of the shell 103.
As shown in FIG. 12, a (play) clearance (hereinafter, referred to as a play clearance) xcex41 is provided between the first slide guide projection 107 and the first slide guide groove 109 and another play clearance xcex42 is provided between the second slide guide projection 108 and the second slide guide groove 110 in order for the first and second slide guide projections 107 and 108 to be inserted into the first and second slide guide grooves 109 and 110 and to be slid smoothly thereon.
The play clearances xcex41 and xcex42 have mutually the same value. Hence, the shutter biasing spring 106 causes the shutter 105 to be pressed against the side portion 103e of the shutter attaching recess 103d of the shell 103 causes the shutter 105 to generate a resultant force to project the shutter 105. At this time, one end of the linkage plate portion 105c of the shutter 105 is projected from the front end surface 103c of the shell 103 by a distance quantity which is approximately the same as the play clearance xcex41.
To suppress the projection, magnitudes of the play clearances xcex41 and xcex42 may be reduced.
However, the reduction of the play clearances xcex41 and xcex42, in turn, worsens a slide guide ability of the shutter 105.
It is, therefore, an object of the present invention to provide the disc cartridge in which the play clearance (xcex41) between the first slide guide projection (107) and the first slide groove (109) is set to be smaller than the other play clearance (xcex42) between the second slide guide groove (110) so that the projection of the linkage plate portion (105c ) of the shutter (105) from the front end surface 103c of the shell (103) can be suppressed without worsening of the slide guide ability of the shutter (105).
According to one aspect of the present invention, there is provided with a disc cartridge comprising: a disc-shaped recording medium; a shell rotatably housing the disc-shaped recording medium; a shutter, the shutter being slidably attached onto the shell and opening and closing a record playback opening provided on upper and lower surfaces of the shell; first and second shutter plate portions, the first and second shutter plate portions constituting the shutter and being overlapped on the upper and lower surfaces of the shell, respectively; a linkage plate portion, the linkage plate portion constituting the shutter, being linked to each one end of the first and second shutter portions, and having an inner surface overlapped on a front end surface of the shell; first and second slide guide projections, the first and second slide guide projections being attached on one end and the other end of the first and second shutter plate portions in a shutter slide direction, respectively; first and second slide guide grooves, the first and second slide guide groove onto which the first and second slide guide projections are inserted to enable the shutter to slide therealong being disposed along the front end surface of the shell; and a spring, the spring biasing the shutter in a direction to close the record playback opening, having one end engaged to a side portion of the shutter onto which the first slide guide projection is installed, and having the other end being engaged to the shell, and wherein a difference in distance between a first distance from the first slide guide projection to an outer surface of the linkage plate portion of the shutter and a second distance from the first slide guide groove into which the first slide guide projection is inserted to the front end surface of the shell is set to be smaller than that between a third distance from the second slide guide groove into which the second slide guide projection is inserted to the front end surface of the shell and a fourth distance from the outer surface of the linkage plate portion of the shutter to the inner surface of the second slide guide projection.
Hence, a play clearance provided between the first slide guide projection and the inner surface of the first slide guide groove opposed against the front end surface of the shell is smaller than another play clearance provided between the second slide guide projection and the inner side surface of the second slide guide groove opposed against the front end surface of the shell. Consequently, a projection of the linkage plate portion of the shutter from the front end surface of the shell can be suppressed.
This summary of the invention does not necessarily describe all necessary features so that the invention may also be a sub-combination of these described features.